Thread: Help sorting out base level computer system.

that is out of my scope of knowledge. i posted the question on the adafruit's forums and that was pretty much the answer i received. as far as dividing the tasks, you could have it all on just the mega and have the second arduino used just as a screen controller (gpu if you will)

Well, running two units probably isn't a bad idea, I don't really know how much I can do all at once on a single board, but I suspect I will be trying to do to much. That was my initial thought on how to divide up the tasks but then I thought, why not use one to run the sensors and a display, and the other to run the buttons, the outputs and the second display.

the mega should be able to handle a lot. the only time i've run into an issue was having a gps module running while trying to control a motor with a pot as a position sensor. it kept overshooting and correcting. the tinygps library is pretty heavy though, so once i took that out of the equation, all worked well. I'm sure it's just an issue of coding (possibly halting all gps related tasks while the h-brdige is positioning the hydrofoil). but for everything that you've talked about, i dont see it as being a problem to run everything on one board (besides the second display)

oh... and i just received a couple of these over the weekend:
http://www.adafruit.com/products/372

they are very easy to use and really quick. i buffered the readings by adding a cap and it smoothed it out very nicely

Cool, so then I can run the second display from an Uno and run everything else from the Mega? Those thermistors look just like what I need, they connect directly to the Arduino right?

yes i believe you can. look into the nano v3. you can get them for about $16 and its the same thing as the uno just a different form factor.

the thermistors work great but they take up analog inputs. so you are a bit limited unless you multiplex... which is an option
http://mayhewlabs.com/products/arduino-mux-shield

Nano v3 for $16, where, where. I don't think the analog inputs will be an issue as the Mega has 14. I only need 6 thermistors, but the wiper, turn signal and brights indicators might also need some analog inputs.

I came across this the other day, I swear it used to be more expensive:

http://www.sparkfun.com/products/11075

I plan on buying one of these for my project, and using it as the same sort of thing you are, general data display and a touch control for different features and functions of the car.

what are you going to use to drive that beast?
edit: n/m... thought it was a raw display

You can either use a MAX232 circuit and run it from the PC's serial port, or run it from an Arduino. If you flash the SGC firmware on it, it acts like a serial graphical LCD.

Or if you're feeling really adventurous, you can use it's own I/O to directly drive relays via transitors on touch screen commands, no Arduino needed :-D but I personally am going to opt for the Arduino option, since the screen has no A/D for temp sensors.


You're on the right track for splitting up tasks on the arduino. Pause GPS parsing while you're doing hbridge management and the like. This is especially an issue when doing Serial related things, since you don't realize exactly how slow 9600 is, until you find out it's taking up 90% of your 16mhz time waiting to send or receive data